Cast stainless steels having a duplex ferrite-austenite structure and containing about 0.08% carbon (max), about 0.1% to 0.4% nitrogen, about 20% to 27% chromium, about 4.5% to 7.5%, nickel, about 2% to 4% molybdenum, with optionally, small additions of copper and/or tungsten, balance essentially iron, have been known. An example is an alloy containing 0.08% carbon (max), 24-27% chromium, 4.5% to 6.5% nickel, 1.3% to 4% copper, 2% to 4% molybdenum, 0.10% nitrogen (min.), balance iron. This alloy is known as "Ferralium". Castings made of such alloys are used in pumps, valves and other parts exposed in service to aggressive liquids such as acids, chlorides and seawater. As is customary in the art, demands have arisen for castings having improved combinations of properties including, in particular, corrosion resistance.